Communication Apparatus and Communication Method

1. A communication apparatus connected to a plurality of slave stations via a network, comprising: a transmitter and a receiver configured to communicate with the plurality of slave stations; and a processor configured to: in response to the transmitter transmitting a delay time measurement frame to each of the plurality of slave stations and the receiver receiving a response frame to the delay time measurement frame from said each of the plurality of slave stations, measure, for said each of the plurality of slave stations, an elapsed time from a first point in time in which the transmitter transmitted the delay time measurement frame to a second point in time in which the receiver received the response frame, and calculate an individual delay time for said each of the plurality of slave stations based on the measured elapsed time for said each of the plurality of slave stations, compare said individual delay time for said each of the plurality of slave stations with an individual delay judgment value, wherein the individual delay judgement is an average of individual delay times calculated in previous communication cycles for a respective slave station, wherein the individual delay time of a current cycle is received after the individual delay times of the previous communication cycles, determine whether an abnormal delay is occurring in at least one of the plurality of slave stations, in response to the determining that the abnormal delay is occurring, identifying a position of a delay element using connection configuration information indicating connection states between the communication apparatus and the plurality of slave stations in the network, and in response to the determining that the abnormal delay is not occurring, updating the individual delay judgement by recalculating the average of the individual delay times using the calculated individual delay time of the current communication cycle and the delay times of the previous communication cycles, wherein, in response to the identified delay element being in a faulty slave station from among the plurality of slave stations, the transmitter transmits a warning indication to the faulty slave station in which the determined abnormal delay has been identified, wherein, in response to the identified delay element being not in one of the plurality of slave stations and being between two of the plurality of slave stations, the transmitter transmits the warning indication to an adjacent slave station from among the plurality of slave stations, which is adjacent to the identified delay element, and wherein, in response to the warning indication, one of the faulty slave station and the adjacent slave station is configured to output an alarm showing an occurrence of the determined abnormal delay.

2. The communication apparatus according to claim 1 , further comprising: a display configured to display the identified position of the delay element on a diagram of the connection states between the communication apparatus and the plurality of slave stations based on the connection configuration information.

3. The communication apparatus according to claim 1 , wherein: in response to the calculated individual delay time deviating from the individual delay judgment value by a predetermined amount or proportion, the processor is further configured to set the calculated delay time as a new delay judgment value for the respective slave station.

4. The communication apparatus according to claim 1 , wherein the network is at least one of: a line type network and a star type network.

5. A communication method in a communication system where a managing station and a plurality of slave stations are connected via a network, the method comprising: transmitting, by the managing station, a delay time measurement frame to a slave station from the plurality of slave stations; starting a timing operation in response to the transmitting of the delay time measurement frame to measure an elapsed time; receiving, by the managing station, a response frame responsive to the delay time measurement frame from the slave station; stopping the timing operation in response to the receiving of the response frame to measure the elapsed time; calculating a delay time of the slave station in a current communication cycle, based on the measured elapsed time; comparing the calculated delay time with a delay judgment value that is an average of individual delay times calculated in previous communication cycles using the timing operation for the slave station, wherein the calculated delay time of the current cycle is received after the individual delay times of the previous communication cycles; determining whether an abnormal delay is occurring in the slave station based on the comparing; in response to the determining indicating that the abnormal delay is occurring in the slave station, identifying a position of a delay element using connection configuration information indicating connection states between the managing station and the plurality of slave stations in the network; and in response to the determining indicating that the abnormal delay is not occurring, updating the delay judgment by recalculating the average of the individual delay times using the calculated delay time in the current cycle and the individual delay times of the previous communication cycles, wherein the transmitting, the starting, the receiving, the stopping, the calculating, the comparing, and the determining is performed for each of the slave stations, wherein, in response to the identified delay element being in a faulty slave station from among the plurality of slave stations, transmitting a warning indication to the faulty slave station in which the determined abnormal delay has been identified, wherein, in response to the identified delay element being not in one of the plurality of slave stations and being between two of the plurality of slave stations, transmitting the warning indication to an adjacent slave station from among the plurality of slave stations, which is adjacent to the identified delay element, and wherein, in response to the warning indication, one of the faulty slave station and the adjacent slave station is configured to output an alarm showing an occurrence of the determined abnormal delay.

6. The communication method according to claim 5 , further comprising: displaying the identified position of the delay element on a diagram of the connection states between the communication apparatus and the plurality of slave stations based on the connection configuration information.

7. The communication method according to claim 5 , wherein the determining comprises, in response to the calculated delay time deviating from the delay judgment value by a predetermined amount or proportion, setting the calculated delay time as a new delay judgment value.

8. The communication method according to claim 5 , wherein the network is at least one of a line type network and a star type network.

9. The communication apparatus according to claim 1 , wherein the communication apparatus manages the network which forms a logical ring comprising the plurality of slave stations, communicates with the plurality of slave stations in a predetermined communication cycle, and synchronizes the plurality of slave stations.

10. The communication apparatus according to claim 1 , wherein a faulty slave station is a slave station that is closer to the delay element than the remaining slave stations from the plurality of slave stations.

11. The communication apparatus according to claim 1 , wherein the transmitter sequentially transmits the delay time measurement frame to said each of the plurality of slave stations and wherein the processor further comprises a timer which measures the elapsed time from a respective delay time measurement frame to a response frame for the respective slave station for said each of the plurality of slave stations and wherein the transmitter transmits to said each of the plurality of slave stations a synchronization frame to synchronize operations of the plurality of slave stations with each other.

12. The communication apparatus according to claim 1 , in response to the processor determining that at least two of the plurality of slave stations have the determined abnormal delay, the processor identifying the position of the delay element as occurring in a line between a first slave station without the determined abnormal delay and a second slave station, which has the determined abnormal delay and which is closest to the communication apparatus based on the connection configuration information.

13. The communication apparatus according to claim 1 , wherein said each of the plurality of slave stations comprise a display configured to display a warning in response to the transmitter transmitting an indicator of the determined abnormal delay.

14. The communication apparatus according to claim 13 , wherein the display is further configured to display a network topology with a location identifier of the identified position of the delay element based on receiving from the communication apparatus the identified position of the delay element.

15. The communication method of claim 5 , wherein the identifying is performed after the transmitting, the starting, the receiving, the stopping, the calculating, the comparing, and the determined is performed for said each of the slave stations.

16. The communication method of claim 5 , wherein the managing station maintains synchronization between the plurality of slave stations via transmitting a synchronization frame to said each of the plurality of slave stations, communicates with the plurality of slave stations in a predetermined communication cycle, and manages a logical ring on the network comprising at least one hub.